** ADVANCE FOR WEEKEND JULY 10-11 ** A white pelican takes flight at the Minidoka National Wildlife Refuge on Thursday, June 24, 2004. The refuge is the only protected nesting grounds for pelican in Idaho. The park is a pleasant and well-maintained place to camp, picnic, fish, watch rare birds and hike. A third of the lake is open to boating. The rest is devoted exclusively to wildlife. Birds are the main attraction at the park and refuge. (AP Photo/Idaho State Journal, Bill Schaefer) ADVANCE FOR WEEKEND JULY 10-11 less

** ADVANCE FOR WEEKEND JULY 10-11 ** A white pelican takes flight at the Minidoka National Wildlife Refuge on Thursday, June 24, 2004. The refuge is the only protected nesting grounds for pelican in Idaho. The ... more

Photo: BILL SCHAEFER

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Abandoned pelican eggs at the Chase Lake National Wildlife Refuge in North Dakota. Thousands of mating pairs of the pelicans inexplicably abandoned their chicks and eggs this year, and scientists so far have been unable to solve the mystery. less

Abandoned pelican eggs at the Chase Lake National Wildlife Refuge in North Dakota. Thousands of mating pairs of the pelicans inexplicably abandoned their chicks and eggs this year, and scientists so far have ... more

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The only pelicans in Medina, N.D., on Wednesday, July 7, 2004, are a plastic one in the towns park and the one on the water tower. Medina is a town famous for pelicans because of it's proximity to the countries largest White Pelican nesting area at Chase Lake Nation Wildlife Refuge. The refuges 28,000 pelicans have abandon their nests and left the area and no one really knows why. (AP Photo/Will Kincaid) less

The only pelicans in Medina, N.D., on Wednesday, July 7, 2004, are a plastic one in the towns park and the one on the water tower. Medina is a town famous for pelicans because of it's proximity to the countries ... more

Photo: WILL KINCAID

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Chase Lake National Wildlife Refuge. Chronicle Graphic

Chase Lake National Wildlife Refuge. Chronicle Graphic

Photo: Todd Trumbull

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Where did all the pelicans go? / Birds abandon chicks, eggs at refuge where they usually breed

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2004-07-13 04:00:00 PDT Chase Lake National Wildlife Refuge, N.D. -- From a bluff looming over a remote section of shoreline here, an observer ought to be able to peer down at swarms of American white pelicans squawking, fluttering and going about the fowl business of breeding.

Instead, it's a scene of baffling desolation, a plain of baby chick carcasses and hundreds of never-to-hatch eggs left behind for the snacking pleasure of hungry coyotes and gulls. The world's largest breeding colony for one of the largest birds in North America is eerily, strangely vacant.

More than 30,000 white pelicans that normally spend the summer procreating at Chase Lake National Wildlife Refuge in central North Dakota returned in their usual droves in April from their winter residence on the Gulf Coast, but then they suddenly dispersed in May after starting an apparently normal breeding season.

Nobody knows why. One biologist, Ron Reynolds of the U.S. Fish and Wildlife Service in Bismarck, said the birds' disappearance is "as mysterious as crop circles." Theories abound, ranging from possible new predators or climate shifts, but they are little more than conjecture. Only humans, with little access to a region that's 10 miles from the nearest paved road, have largely escaped suspicion.

"Obviously, this is a shock to us," said Chase Lake refuge manager Mick Erickson, also a wildlife biologist. "To see something like this happen within a relatively short period of time is both surprising and disheartening. We just don't have any concrete answers as to what kind of event could have caused a mass abandonment like this. ... We've never heard of any event of this scale ever happening." Chase Lake, about 60 miles east of Bismarck, was established as a protected area in 1908 by President Theodore Roosevelt, to save the dwindling number of pelicans from hunters at a time when the feathers were fashionable in hats and other garments. There were then about 50 breeding pairs; the colony peaked in 2000 at 17,500 pairs on the 4,385-acre site.

None of the other 27 breeding colonies in 11 states and four Canadian provinces comes close to those figures, says pelican expert Tommy King of the U.S. Department of Agriculture's Animal and Plant Health Inspection Service based in Starkville, Miss.

During a normal mating season, the white pelicans -- which measure 6 feet from bill to tail and have a wingspan of nearly 10 feet -- build nests and lay as many as two eggs in May. Both parents take turns either squatting on the eggs to incubate them or tending to newborn chicks while the other forages in a 100-mile radius for fish or salamanders for food.

Mating only occurs once a year, so a disruption like this means a slowdown in reproduction. The birds are not a threatened or endangered species, though, so the incident is not viewed as a serious setback to the species' survival, Reynolds said.

Since May, the Chase Lake birds appear to have dispersed across the Dakotas, Minnesota and southern Canada.

"Normally we may not see any at all this time of year, but the last three or four weeks we've seen 1,000 to several thousand," said Wayne Brininger, manager of the Tamarac National Wildlife Refuge in Detroit Lakes, Minn., about 200 miles east of Chase Lake. "They aren't breeding here. They're just loafing on our lakes and feeding."

Researchers first noticed the abandonment at Chase Lake in late May when they made a routine visit to a peninsula where most of the breeding usually occurs only to find few adult pelicans, some chick carcasses and hundreds of eggs raided by coyotes and gulls. The remaining birds were strikingly nervous around the humans, taking flight when researchers came near instead of merely walking calmly away as they normally do, said biologist Marsha Sovada of the Northern Prairie Wildlife Research Center in nearby Jamestown, a branch of the U.S. Geological Survey.

That gave rise to the first theory, that coyotes had moved into the area in unusual numbers and scared off the colony. The West Nile virus had killed off thousands of young chicks in 2003, so researchers wondered if the coyotes feasted on those remains during the winter and decided the area was a viable hunting ground for them during the summer, too.

That theory was suspect because there was no littering of adult pelican carcasses to suggest such depredation, and it failed to explain the abandonment on one of two islands in the lake where nesting also occurs. Coyotes wouldn't have had access to that area, Sovada said.

The same thinking is ruling out a disease outbreak; adult birds would probably be found dead alongside their young.

By early June, the second island where breeding occurs also was abandoned. King attached global positioning chips to four of the pelicans on the second island in late May before they dispersed and found they fled the area between May 30 and June 2. Their paths -- each went in a different direction -- shows that something prompted the birds to fan out in haphazard directions, further deepening the mystery.

"This is pretty much an odd, freaky thing," said King, who has been studying the migratory and breeding habits of Chase Lake pelicans for a decade.

Another theory blames a cool, wet spring for stressing the birds and making food more difficult to find. Both May and June were among the coldest on record for the area, National Weather Service meteorologist Janine Vining said, and the Chase Lake region had 3 inches more rain in May than usual.

"Abnormally cool weather puts greater physical demands on adult pelicans and may have changed the availability of food source," said Reynolds. "That doesn't mean the food isn't out there, but it may be harder to access if small fish are not swimming in shallow waters where the pelicans forage. These birds may need more food and, at the same time, they're balancing the demands of nesting and raising chicks.

"It could be that amid a little bit of added strain, they chose survival over reproduction," he said.